A skin of a human is a primary barrier of a human body and has a function protecting the organ in a body from a stimulus of an outer circumstance such as a change of a temperature and moisture, ultraviolet ray, pollutant, and the like, and undergoes a change by various inner and outer factors. That is, internally, a secretion of various hormones regulating metabolisms is reduced, a function and activity of immune cells are lowered, and thus, a biosynthesis of immune proteins necessary for an body and proteins constituting the body are decreased, and externally, a content of ultraviolet ray reaching the surface of an earth is increased due to a destruction of an ozone layer and free radicals, active harmful oxygen and the like are increased as an environment pollution is deepening, and thus various changes are raised such as that the thickness of a skin is reduced, a wrinkle is increased, an elasticity of the skin is reduced, as well as, a bloom of the skin is dull, a trouble of the skin is often occurred, chloasmas, freckles and age spots are increased, the bloom of the skin becomes worse, a skin tone becomes dark, and the like.
In order to prevent changes of the skin condition due to the internal or external factors and to maintain the healthy skin condition, there has been efforts to improve the skin condition by adding the physiological active materials obtained from the already known various animals, plants, microorganisms and the like to cosmetics and using it.
Meanwhile, green tea uses leaves of Camellia sinensis, and is consumed as a medical beverage and healthy drinks, and the medical effects of the green tea is due to flavonoid-based ingredients. Several of triterpenoid saponin extracted from leaves of Camellia sinensis is reported as bitter principle and triterpenoid saponin can be also extracted from other parts of Camellia sinensis, i.e., seeds, flower buds, roots, etc.
In particular, triterpenoid saponin derived from roots of Camellia sinensis provides an excellent skin improvement effect such as anti-aging, skin whitening, skin moisturizing and the like, but since it has a toxicity itself, there are problems in the light of the skin safety in the case of that it is used in large amounts, and thus, there is a need to lower the toxicity of the saponin derived from roots of Camellia sinensis. 